No details of the contingency plan have been announced, but it's clear that Trump is seen as a major threat to Mexico.

He has threatened to slap a 35% tariff on goods made by U.S. companies in Mexico and sold in the United States. Exports make up one third of Mexico's economy and almost all of them go to America.

Trump claims he will tear up NAFTA, the free trade deal between Canada, Mexico and America if it isn't renegotiated. And he wants to build a wall on the U.S.-Mexico border that he claims Mexico will pay for. (Mexico's president says Mexico won't pay for it).

"It's a lose-lose proposition," Arturo Sarukhan, the former Mexican ambassador to the U.S., told CNN Friday. "The only losers will be the American and the Mexican peoples."

Trump's negative rhetoric is already hurting Mexico's currency, the peso. It's down 9% this year, partially due to Trump. Whenever Trump's poll numbers have improved this year, the peso has gone down.

A weakening currency is not all bad news: it makes Mexico's exports more affordable -- and attractive -- to foreign buyers, and when Mexicans send money home to loved ones, they're getting more and more pesos.